Task 1.

1) were
2) were
3) had
4) were
5) had, would come

Task 2.

1) if I won a lot of money, I would buy a house to my parents
2) if I met an alien, I would talk with him
3) if I could do magic, I would make this world a better place
4) if I got lost in the forest, I would try to find something, that can help me

Task 3.

1) if I didn't have friends, I would be lonely
1) if only they knew the truth
3) I wish I were in your shoes
4) If only I could buy a new computer

Task 4.

1) had left
2) called
3) help
4) would have got
5) hadn't failed

Variant2
Task 1

1) didn't
2) were
3) called me, would tell
4) found
5) will be, wouldn't

Task 2

1) if I saw a ghost, i would scream
2) is I saw a burglar in my room, I would really really scary and try to call to police
3) if I saw an accident, I would tell my parents or police about it
4) if I got fat, I would go to the gym 

Task 3

1) If she wanted to win, she would have trained hard
2)  I wish you could come to my party
3) if we stayed at home, I would have made dinner
4) I wish I were a fairy

Task 4

1) would have met
2)  had got
3) had been
4) had been
5) have behaved